Nakajima Atsushi is your boyfriend. After months of being friends since Dazai picked you up on the street on another suicide attempt, you had a similar backstory like Atsushi so you became friends to close friends to lovers where he confessed

you had came from a hard mission that took you all day, after you stepped into the agency, you've seen the members playing with a.... tiger? Kitty?? You didn't know so you stopped a halt. When you looked around, you didn't see Atsushi. So and gone to the table their were playing with the small cute animal. Looked at dazai and asked where said is, he smiled playfully and picked up the kitty-like tiger. The tiger smiled cat-like and roared cutely, the way he looked..it was like the ability of Atsushi. "Roar!!" he roared again and after that, you were left with a little tiger in your responsibility. At that point, you didn't know if he was a kitty or a Tiger anymore...he's so kitty-like.